Use of gingerone or derivatives thereof for reducing or delaying the signs of skin ageing

ABSTRACT

The present invention relates to the cosmetic use of at least one compound of general formula (I): 
     
       
         
         
             
             
         
       
     
     in which:
         R 1  represents a methyl or ethyl radical;   R 2  represents a hydrogen atom or a methyl or ethyl radical;   R 3  represents a linear C 1 -C 6  or branched C 3 -C 6  alkyl radical, or a linear C 2 -C 6  or branched C 3 -C 6  alkenyl radical; and   X represents ═O or —OH,
 
as an agent for reducing and/or delaying the signs of skin ageing.

The present invention relates to the field of ageing and of the signsthat are associated therewith, on the skin. It relates in particular tothe adjustment of the equilibrium between the proliferation and thedifferentiation of the epidermal cells.

Women, or even men, currently have a tendency to want to look young foras long as possible and consequently seek to tone down the signs of skinageing, which result in particular in wrinkles and fine lines, athinning of the epidermis and/or a flaccid and withered skin appearance.In this regard, the advertising and fashion industries mention productsfor retaining radiant and wrinkle-free skin, signs of youthful skin, aslong as possible, all the more so since physical appearance has aneffect on the psyche and/or on morale.

The skin constitutes a physical barrier between the body and itssurroundings. It is constituted of two tissues: the epidermis and thedermis.

The dermis provides the epidermis with a solid support. It is also itsnourishing element. It is formed mainly from fibroblasts and anextracellular matrix, which is itself composed mainly of collagen,elastin and a substance known as ground substance, these componentsbeing synthesized by the fibroblast. Leukocytes, mast cells or elsetissue macrophages are also found therein. It also contains bloodvessels and nerve fibres.

The epidermis is a desquamating pluristratified epithelium that is 100μm thick on average and is conventionally divided into a basal layer ofkeratinocytes that constitutes the germinal layer of the epidermis, aspinous layer constituted of several layers of polyhedral cellspositioned on the germinal cells, a granular layer constituted offlattened cells containing distinct cytoplasmic inclusions, keratohyalingranules, and finally an upper layer known as the cornified layer (orstratum corneum), constituted of keratinocytes at the terminal stage oftheir differentiation, known as corneocytes. These are mummifiedanucleated cells which derive from keratinocytes. The stack of thesecorneocytes constitutes the cornified layer that is responsible, interalia, for the barrier function of the epidermis, i.e. it constitutes abarrier against external attacks, especially chemical, mechanical orinfectious attacks and it also makes it possible to protect the bodyfrom water loss.

Epidermal differentiation follows a process of continuous and orientedmaturation in which the basal keratinocytes transform while migrating soas to result in the formation of corneocytes, dead cells that arecompletely keratinized. This differentiation is the result of perfectlycoordinated phenomena which will result in the thickness of theepidermis being kept constant and thus ensure the homeostasis of theepidermis. This goes through a regulation of the number of cells thatenter into the differentiation process and of the number of cells thatdesquamate. In the course of the normal desquamation process, only themost superficial corneocytes detach from the surface of the epidermis.

Keratins are insoluble proteins produced by the epithelial cells in theform of structurally well organized filaments. These proteins are themain marker of differentiation since throughout epidermaldifferentiation, various types of keratin will be more or less expressedby the keratinocytes.

Other proteins, associated with keratins, play very important roles inthe skin. Filaggrin (or filagrin), a protein present in keratohyalingranules, is produced during the final stages of the differentiation ofthe epidermis. It is especially involved in the maturation process ofthe cornified layer by enabling type I and type II keratins to bearranged into coils. This protein thus enables the formation of thecytoplasmic matrix of the surface corneocytes which in particular givesthe skin its normal thickness, its smooth appearance and itslight-reflecting properties. Furthermore, via its degradation withincorneocytes, filaggrin provides water-soluble substances having a highosmotic power (natural moisturizing factors or NMFs) that enable a goodhydration of the cornified layer of the skin to be maintained and thusavoid the feelings of “dry skin”. Filaggrin therefore enables thebarrier function of the epidermis to be maintained and makes it possibleto avoid drying out the skin.

In the course of chronobiological ageing, the thickness of the epidermisis reduced, maturation of the keratinocytes is imperfect andkeratinization no longer leads to an even and homogeneous cornifiedlayer being created. It is also known that prolonged and/or repeatedexposures to the sun lead to quite similar results on the epidermis.This is photoinduced ageing. It is also known that, at the menopause,skin ageing accelerates, the thickness of the epidermis decreases, womencomplain of their skin tightening and that it takes on the look of “dryskin”, or even of the appearance of xerosis.

Surprisingly, the inventors have demonstrated that gingerone and some ofthe derivatives thereof increased the expression of filaggrin in thekeratinocytes. As filaggrin is a marker of the differentiation ofkeratinocytes, gingerone and some of the derivatives thereof thereforehave an effect of stimulating the differentiation of these cells andthus the maturation of the cornified layer. They thus enable the skin toretain or regain a normal thickness, to also have a smooth appearance,i.e without, or with fewer, wrinkles and fine lines than before theiruse and a more radiant, less dull complexion.

Furthermore, since filaggrin is involved in the skin hydration process,by increasing the expression of this protein in keratinocytes, thesecompounds enable the skin to fully carry out its barrier function whileavoiding, in particular, the drying out thereof. They therefore make itpossible to reestablish or maintain good hydration of the skin.

These compounds therefore prove particularly advantageous for combatingthe appearance of the signs of skin ageing and for combating the dryingout of the skin, whether or not this is linked to the ageing thereof.

Gingerone (INCI name: Zingerone), is a phenolic compound from thevanilloid family. Its formula and those of several of its derivativesare given below. Ginger (Zingiber officinale), mango, cranberry orraspberry may be natural sources of gingerone. Ginger, and in particularginger oleoresin, is however the main source thereof. This molecule isto a large extent responsible for the hot flavour of ginger.

Gingerone has already been cited among the ingredients of topicalanti-ageing care compositions but it was used as a blood circulation“accelerator” (JP 2004323401, JP 2005066831) or as a hyperemizing agent(EP 1 938 789) or as an antioxidant (EP 1 932 514) or as a caustic,bitter or acid substance (JP 2004210656).

To the knowledge of the inventors, gingerone and some of the derivativesthereof have never been described as being pro-differentiating forkeratinocytes and as being able to be used specifically for treating ordelaying the appearance of the signs of skin ageing.

One subject of the present invention is thus the use of at least onecompound of general formula (I):

in which:

-   -   R₁ represents a methyl or ethyl radical;    -   R₂ represents a hydrogen atom or a methyl or ethyl radical;    -   R₃ represents a linear C₁-C₆ or branched C₃-C₆ alkyl radical, or        else a linear C₂-C₆ or branched C₃-C₆ alkenyl radical; and    -   X represents ═O or —OH,        as an agent for reducing and/or delaying the signs of skin        ageing.

Preferably, these compounds are of general formula (I) in which:

-   -   R₁ represents a methyl or ethyl radical;    -   R₂ represents a hydrogen atom or a methyl or ethyl radical;    -   R₃ represents a C₁-C₆ linear alkyl; and    -   X represents ═O or —OH.

In particular, use will be made of compounds of general formula (I) inwhich:

-   -   R₁ represents a methyl or ethyl radical;    -   R₂ represents a hydrogen atom or a methyl or ethyl radical;    -   R₃ represents a C₁-C₆ linear alkyl; and    -   X represents ═O.

According to the present invention, the compound of general formula (I)mentioned above will preferably be chosen, alone or as a mixture, fromthe following compounds:

Number and name of the compound Formula of the compound Compound 1:Gingerone or Zingerone or vanillylacetone CAS number: 122-48-5

Compound 2: 4-(3-ethoxy-4- hydroxyphenyl)-2- butanone (7Ci) or ethylgingerone CAS number: 569646-79-3

Compound 3: 4-(3-ethoxy-4- hydroxyphenyl)-2- butanol

Compound 4: 1-paradol CAS number: 53171-99-6

Compound 5: 4-(3-methoxy-4- hydroxyphenyl)- 3-methylbutane- 2-one CASnumber: 83092-97-1

Compound 6: 3-paradol CAS number: 53172-01-3

Compound 7: 1-(4-hydroxy-3- methoxyphenyl) nonan-3-one CAS number:53172-03-5

The preferred compound will be chosen from gingerone (or zingerone) orethyl gingerone. The gingerone may be, for example, supplied by thecompany Aldrich. Most preferred is ethyl gingerone.

Compounds 2 and 7 may be, for example, supplied by the companySinoChemExper.

The compounds of general formula (I), as targeted above, could be usedin the form of a more or less purified molecule of natural or syntheticorigin. They will preferably be of natural origin. In particular, someof these compounds could be provided in the form of plant extractscontaining them, and especially in the form of an extract of ginger, ofmango, of cranberry and/or of raspberry.

Such compounds may be synthesized via synthesis pathways known in theprior art. They may in particular be prepared from commercial vanillinor ethyl vanillin. Gingerone, for example, could be obtained via thecondensation of vanillin by acetone, followed by a hydrogenation.

The expression “cutaneous signs of ageing” is understood to mean anymodification in the external appearance of the skin due to ageing,whether chronobiological and/or photoinduced, such as, for example,wrinkles and fine lines, withered skin, flaccid skin, slack skin,thinned skin, dry skin, dull skin that lacks radiance, heterogeneity ofthe complexion and of the surface of the skin. The signs ofchronobiological or chronological ageing (also known as chronoageing)correspond to internal degradations of the skin due to the intrinsicageing of the individuals. The signs of photoinduced ageing (orphotoageing) correspond to internal degradations of the skin followingexposure to ultraviolet radiation.

The term “skin” is understood to mean, for the purposes of theinvention, the whole of the body covering, and in particular the skin,mucous membranes and scalp.

The reduction of the signs of skin ageing and/or the delaying of theirappearance, via the use of the compounds according to the presentinvention, takes place in particular owing to the increase orimprovement in the differentiation of the epidermal cells and/or theincrease or stimulation in particular of the expression of filaggrin inthe epidermal keratinocytes.

Preferably, the compositions used according to the invention arecosmetic compositions, i.e. they are intended to improve the aestheticappearance of the individual.

The use according to the present invention is especially effective forcombating the signs, in particular aesthetic signs, of chronobiologicaland/or photoinduced ageing of the epidermis. Through the presentinvention, combating the signs of chronobiological ageing of the skinwill preferably be targeted.

The present invention is thus effective in any person regardless oftheir age. When combating the signs of chronobiological ageing, theindividuals preferably targeted will be individuals of more than 30years old, preferably more than 40 years old.

The signs of skin ageing are preferably chosen from the appearance ofwrinkles and fine lines and/or the weakening and/or the slackeningand/or the withering and/or the thinning and/or the dryness and/or thedull and/or non-radiant appearance and/or the complexion and/or theheterogeneous surface of the skin.

Through the present invention, skin having a more youthful appearanceand better hydrated skin are therefore obtained.

The compound of general formula (I) as targeted above is present, in acomposition comprising a physiologically acceptable medium, in a contentbetween 0.1% and 10% by weight relative to the total weight of saidcomposition.

A “physiologically acceptable medium” is, according to the invention, acosmetically acceptable medium that is compatible with the skin, themucous membranes, the nails and/or the hair.

The expression “cosmetically acceptable medium” is understood to mean amedium that has no unpleasant appearance, and that does not cause theuser any unacceptable stinging, tautness or redness.

The physiologically acceptable medium will be adapted to the nature ofthe support onto which the composition is to be applied, and also to theform in which the composition is intended to be packaged, in particularsolid or fluid at room temperature and atmospheric pressure.

The composition is preferably suitable for topical application.

For an administration via topical application to the skin and/or themucous membranes, the composition according to the invention of coursecomprises a cosmetically acceptable support, i.e. a support that iscompatible with the skin, the mucous membranes, the nails, the hair, andmay be in any galenic form normally used for a topical application, inparticular in the form of an aqueous, aqueous-alcoholic or oilysolution, an oil-in-water or water-in-oil or multiple emulsion, anaqueous or oily gel, a liquid, pasty or solid anhydrous product, asuspension or a dispersion; for example a dispersion of oil in anaqueous phase using spherules, it being possible for these spherules tobe polymeric nanoparticles, such as nanospheres and nanocapsules, orbetter still lipid vesicles of ionic and/or nonionic type.

This composition may be more or less fluid and may have the appearanceof a white or coloured cream, an ointment, a milk, a lotion, a serum, apaste or a foam. It can optionally be applied to the skin in aerosolform. It can also be in solid form, for example in the form of a stick.It can be used as a care product or as a cleansing product or as amakeup product.

In a known manner, the composition of the invention may containadjuvants that are common in the cosmetic and dermatological fields,such as hydrophilic or lipophilic gelling agents, hydrophilic orlipophilic active agents, preserving agents, antioxidants, solvents,fragrances, fillers, screening agents, pigments, chelating agents, odourabsorbers and colorants. The amounts of these various adjuvants arethose conventionally used in the fields under consideration, for examplefrom 0.01% to 20% of the total weight of the composition. Depending ontheir nature, these adjuvants may be introduced into the fatty phase,into the aqueous phase, into the lipid vesicles and/or into thenanoparticles.

When the composition of the invention is an emulsion, the proportion ofthe fatty phase may range from 5% to 80% by weight and preferably from5% to 50% of the total weight of the composition. The oils, emulsifiersand coemulsifiers used in the composition in emulsion form are chosenfrom those conventionally used in the field under consideration. Theemulsifier and the coemulsifier are present in the composition in aproportion ranging from 0.3% to 30% by weight and preferably from 0.5%to 20% of the total weight of the composition.

As oils that can be used in the invention, mention may be made ofmineral oils, oils of plant origin (apricot oil, sunflower oil), oils ofanimal origin, synthetic oils, silicone-based oils and fluorinated oils(perfluoropolyethers). As fatty substances, use may also be made offatty alcohols (cetyl alcohol), fatty acids and waxes (beeswax).

As emulsifiers and coemulsifiers that can be used in the invention,mention may for example be made of polyethylene glycol fatty acid esterssuch as PEG-40 stearate and PEG-100 stearate, and polyol fatty acidesters such as glyceryl stearate and sorbitan tristearate.

As hydrophilic gelling agents, mention may particularly be made ofcarboxyvinyl polymers (carbomer), acrylic copolymers such asacrylate/alkyl acrylate copolymers, polyacrylamides, polysaccharides,natural gums and clays, and, as lipophilic gelling agents, mention maybe made of modified clays such as bentones, metal salts of fatty acids,hydrophobic silica and polyethylenes.

According to one advantageous embodiment, the compositions according tothe invention will contain at least one other active agent chosen fromanti-UV screening agents, moisturizers, depigmenting agents,anti-glycation agents, NO-synthase inhibitors, agents for stimulatingthe synthesis of dermal or epidermal macromolecules and/or forpreventing their degradation, agents for stimulating fibroblast orkeratinocyte proliferation, myorelaxants or dermo-decontracting agents,tensioning agents, agents for combating pollution or free-radicalscavengers, calmatives and active agents that act on the energymetabolism of cells.

The amount of these additional active agents could vary to a largeextent and will be for example from 10⁻⁶% to 20% by weight, especiallyfrom 0.001% to 10% by weight relative to the total weight of thecomposition.

The agents for stimulating fibroblast proliferation that may be used inthe composition according to the invention may be chosen, for example,from plant proteins or polypeptides, extracted especially from soybean(for example a soybean extract sold by the company LSN under the nameEleseryl SH-VEG 8® or sold by the company Silab under the trade nameRaffermine®); and plant hormones such as gibberellins and cytokinins.

The agents for stimulating keratinocyte proliferation that can be usedin the composition according to the invention especially compriseretinoids such as retinol and esters thereof, including retinylpalmitate; adenosine, cinnamic acid and derivatives thereof, lycopeneand derivatives thereof; phloroglucinol; the walnut meal extracts soldby the company Gattefossé; and the extracts of Solanum tuberosum sold bythe company Sederma.

Preferably, for the implementation of the invention, the compound ofgeneral formula (I) as described above, and/or the compositioncontaining it, will be applied to the part of the skin to be treated, inparticular to the face, the neck or the hands, daily or several timesdaily; the application will be repeated every day for a variable perioddepending on the effects desired, generally from 3 to 6 weeks, but whichcould be extended or carried out continuously.

The compound of general formula (I) as described above or thecomposition containing it will preferably be applied to the areas ofskin affected by the signs of ageing that it is desired to combat.

For an oral administration, the composition of the invention may be inany suitable form, particularly in the form of a solution to be takenorally, a tablet, a gel capsule, a capsule or alternatively anutritional food or a nutritional supplement.

Said composition additionally comprises at least one appropriateexcipient suitable for oral administration.

In the case of active agents or of compositions according to theinvention being taken orally, the oral administration may be daily orseveral times daily, for example morning and evening. It could becontinued for several weeks and/or several months, depending on theeffects desired.

The examples given below are presented as non-limiting illustrations ofthe invention.

EXAMPLES 1. Method of Preparing a Compound According to the Invention

The method of preparing these compounds of general formula (I) may be,for example, the following:

The method of preparing compound 3 comprises a supplementary reductionstep:

The compounds according to the invention are prepared here either fromcommercial vanillin (CAS: 121-33-5), or from commercial ethyl vanillin(CAS: 121-32-4).

2. Demonstration of the Activity of a Compound According to theInvention

The in vitro effect of gingerone (compound 1, the chemical formula ofwhich is given above) on keratinocyte differentiation is studied. Theexpression and the location of the marker of filaggrin differentiationare especially studied in keratinocytes in culture which thus makes itpossible to evaluate the capacity of this compound to increase thedifferentiation of these cells.

Procedure:

Normal human keratinocytes (NHEKs) were cultured at 37° C. and 5% CO₂for 24 h in a complete SFM medium until moderate confluence wasobtained. A complete SFM medium is an SFM culture medium supplementedwith pituitary extract (25 μg/ml), EGF (0.25 ng/ml) and gentamicin (25μg/ml).

At the end of the incubation, the medium was withdrawn and replaced withculture medium that did or did not contain various concentrations of thetest product or reference molecules. Calcium chloride and retinoic acid,which are known respectively as a stimulator and as an inhibitor of thekeratinocyte differentiation, were used as reference molecules for thistest. The keratinocytes were then incubated for 144 hours. Thetreatments were carried out in triplicate (n=3).

At the end of the incubation, the culture medium was removed and thecells were rinced, fixed, permeabilized then labelled with the primaryantibody targeted against the filaggrin protein of interest (in situimmunolabelling). This antibody was then revealed by a secondaryantibody coupled to a fluorochrome (GAM-Alexa 488). At the same time,the nuclei of the cells were stained with Hoechst 33258 (bisbenzimide).

Image acquisition was carried out using an INCell Analyzer™1000 machine.The labels were quantified by measuring the fluorescence intensity ofthe proteins relative to the number of nuclei identified by the Hoechstproduct.

Results

The results are given in Table 1 below:

TABLE 1 % relative to Treatment the control Control complete SFM 100 medium CaCl₂ 1.5 mM  158** Retinoic acid 10⁻⁷ M   3** Gingerone 2 μg/ml133* 20 μg/ml 151* Significant difference relative to the control medium(*p < 0.05 and **p < 0.01).

-   -   Under the experimental conditions of this study, the treatment        with calcium chloride, pro-differentiating reference molecule,        substantially increases the expression of filaggrin by the        keratinocytes (+58% relative to the control).    -   Under the experimental conditions of this study, the treatment        with retinoic acid, anti-differentiating reference molecule,        substantially decreases the expression of filaggrin by the        keratinocytes (−97% relative to the control).    -   The treatment with gingerone at 2 μg/ml and 20 μg/ml        significantly and dose-dependently stimulates the expression of        filaggrin (+33% and +51% respectively relative to the control)        by the keratinocytes.

Conclusion

Gingerone significantly and dose-dependently increases the expression ofthe filaggrin protein in normal human epidermal keratinocytes.

The results obtained thus translate into an increase in epidermaldifferentiation. Gingerone therefore has a pro-differentiating effect onnormal human keratinocytes and therefore can thus reduce and/or delaythe signs of skin ageing.

3. Composition Examples 3.1. Lotion

A lotion is prepared, comprising (% by weight):

compound tested in Example 1 (gingerone) 0.75% glycerol   2% ethylalcohol   20% demineralized water qs 100%

The composition according to the invention applied daily to the facemakes it possible to combat the signs of skin ageing.

3.2. Facial Gel

A facial gel is prepared, comprising (% by weight):

glyceryl polyacrylate (Norgel) 30%  polyacrylamide/C13-14isoparaffin/laureth-7 (Sepigel 305) 2% silicone oil 10%  compound 1(gingerone) 5% water qs 100%

-   -   The composition according to the invention applied daily to the        face makes it possible to combat the signs of skin ageing.

1-8. (canceled) 9: A method for combating signs of chronobiologicalageing of an epidermis, comprising: applying to the epidermis a compoundof general formula (I):

wherein: R₁ is an ethyl radical; R₂ is a hydrogen atom or a methyl orethyl radical; R₃ is a linear C₁-C₆ or branched C₃-C₆ alkyl radical, ora linear C₂-C₆ or branched C₃-C₆ alkenyl radical; and X is ═O or —OH.10: The method according to claim 9, wherein R₃ is a C₁-C₆ linear alkyl.11: The method according to claim 9, wherein the compound of generalformula (I), alone or as a mixture, is at least one selected from thegroup consisting of:

12: The method according to claim 9, wherein the compound is ethylgingerone. 13: The method according to claim 9, wherein thechronobiological signs of skin ageing are an appearance of wrinkles andfine lines weakening, withering, thinning, dryness, or dull ornon-radiant appearance, complexion, heterogeneous surface of the skin,or any combination thereof. 14: The method according to claim 9, whereinthe compound is present in a composition comprising a physiologicallyacceptable medium, in a content between 0.1% and 10% by weight relativeto a total weight of the composition. 15: The method according to claim9, wherein the compound is applied in a cosmetic composition comprisingthe compound of general formula (I) in an amount of 0.1 to 10% by weightrelative to a total weight of the cosmetic composition. 16: The methodaccording to claim 15, wherein the cosmetic composition is a lotion. 17:The method according to claim 15, wherein the cosmetic composition is agel. 18: A method for treating chronobiological skin aging in a subjectin need thereof, comprising: applying to the skin of the subject aneffective amount of a compound of formula (I):

wherein: R₁ is an ethyl radical; R₂ is a hydrogen atom or a methyl orethyl radical; R₃ is a linear C₁-C₆ or branched C₃-C₆ alkyl radical, ora linear C₂-C₆ or branched C₃-C₆ alkenyl radical; and X is ═O or —OH.19: The method according to claim 18, wherein R₃ is a C₁-C₆ linearalkyl. 20: The method according to claim 18, wherein the compound ofgeneral formula (I), alone or as a mixture, is at least one selectedfrom the group consisting of:

21: The method according to claim 18, wherein the compound is ethylgingerone. 22: A method of treating signs of chronobiological ageing ofan epidermis of a subject in need thereof, comprising: stimulatingfilaggrin protein expression in a human epidermal keratinocyte byapplying to a skin of the subject a compound of general formula (I):

wherein: R₁ is an ethyl radical; R₂ is a hydrogen atom or a methyl orethyl radical; R₃ is a linear C₁-C₆ or branched C₃-C₆ alkyl radical, ora linear C₂-C₆ or branched C₃-C₆ alkenyl radical; and X is ═O or —OH.23: The method according to claim 22, wherein the compound is ethylgingerone. 24: The method according to claim 22, comprising treatingsigns of chronobiological ageing in a subject suffering from internaldegradations of the skin due to intrinsic ageing of the individual,rather than due to exposure to ultraviolet radiation.